Italy’s West Nile Virus Spread Accelerates with Warming Climate
Italy has recorded over 650 West Nile virus infections this year, roughly half of all European cases, as warmer temperatures and longer summers enable mosquitoes to spread the disease across a wider area and for more months. The country’s extensive surveillance network and climate‑driven expansion…
By Felo News Desk · Published
Italian health authorities have confirmed that the West Nile virus (WNV) is spreading farther and longer across the country, a trend linked to rising temperatures and extended warm seasons. More than 650 infections have been reported in Italy so far this year, accounting for about half of all cases recorded in Europe.
WNV in Italy: A Growing Threat
West Nile virus has been considered endemic in Italy since 2020, when cases began to surge. The disease is now reported every summer and into early fall, with most infections occurring in people who do not show symptoms. About 80% of infected individuals remain asymptomatic, while the remainder experience mild flu‑like symptoms. Severe neurological complications are rare, typically affecting older adults or those with underlying health conditions.
Experts say this year’s case numbers are broadly in line with recent seasons, but warmer temperatures are expected to push the transmission season further into the autumn, sometimes as late as November. This extended period allows mosquitoes to reproduce more rapidly and increases the window during which they can spread the virus to humans.
Climate Change and Mosquito Dynamics
Antonino Bella, a senior researcher at Italy’s National Institute of Health (ISS), explains that higher temperatures linked to climate change help mosquitoes reproduce and extend the transmission season. The result is a higher likelihood that infected mosquitoes will bite people. Bella notes that areas once largely unaffected are increasingly reporting infections, reflecting a gradual expansion of the virus across the country.
Marc‑Alain Widdowson, head of the Pandemic Threats, Communicable Diseases and AMR Division at the World Health Organization’s Europe office, cautions that while climate change is not the sole factor, a warming climate does lengthen the mosquito season and improves the virus’s survival. Widdowson also highlights other contributing trends such as loss of biodiversity and changes in land use, which can favor species that are efficient reservoirs of WNV.
European Context and Surveillance
Italy’s experience has drawn attention from European countries located farther north. A Belgian research team visited the ISS last May to study Italy’s research and surveillance system after the country began recording locally acquired WNV cases. The Netherlands has reported more than two dozen cases this year, the first since 2020, and has recorded several deaths, according to its public health institute.
Italy’s extensive monitoring network tracks mosquitoes, birds, blood donors and human infections. This comprehensive surveillance helps explain why the country detects so many cases and provides valuable data for neighboring nations. The European Centre for Disease Prevention and Control (ECDC) warned in June that Europe’s warming trend—characterized by heat waves, flooding, and longer, warmer summers—creates favorable conditions for invasive mosquito species such as Aedes albopictus and Aedes aegypti.
Aedes aegypti, known to transmit dengue, yellow fever, chikungunya, Zika and West Nile viruses, has been established in Cyprus since 2022 and may spread to other European countries. A decade ago, Aedes albopictus was established in eight European countries, affecting 114 regions. This year, the mosquito is established in 13 countries and 337 regions, according to the ECDC.
What Happens Next?
Italian authorities are continuing to monitor mosquito populations and human cases closely. Public health officials urge the public to take preventive measures, such as using insect repellent, wearing long sleeves and pants, and eliminating standing water where mosquitoes breed. The European Union and WHO are coordinating efforts to share surveillance data and develop strategies to mitigate the spread of WNV and other vector‑borne diseases.
While the current case numbers align with recent seasons, the ongoing warming trend suggests that the virus’s reach and duration may expand further in the coming years. Continued research, surveillance, and public education will be essential to protect populations across Europe.
Key facts
- Italy reports 650+ West Nile cases, half of all European cases this year
- Warming temperatures extend mosquito breeding season into November
- Italian surveillance network tracks mosquitoes, birds, blood donors, and human infections
- Northern European countries are monitoring Italy’s model and increasing case counts
- Invasive mosquitoes like Aedes albopictus and Aedes aegypti are expanding across Europe
Why it matters
The spread of West Nile virus in Italy highlights how climate change can extend disease‑vector seasons, increasing public health risks across Europe.
Frequently asked questions
What is West Nile virus?
West Nile virus is a mosquito‑borne virus that can cause flu‑like illness or severe neurological disease in humans.
How many people are affected in Italy?
Over 650 infections have been reported in Italy this year, with about 80% showing no symptoms.
Why is the virus spreading farther?
Rising temperatures and longer warm seasons enable mosquitoes to reproduce more and survive longer, extending the transmission window.
What measures can people take?
Use insect repellent, wear long sleeves and pants, and eliminate standing water to reduce mosquito breeding sites.
